The present invention relates to a paper sheet, and more particularly, to a paper sheet useful a basesheet for high quality coated papers or in carbonless record sheets. More particularly, it relates to a sheet comprising a primary sheet having a layer of pulp fines on at least one surface thereof.
Pulp fines comprise ray cells, parenchyma cells, fibrils, and fibers. Ray cells are short cells which are chiefly parenchymatous and make up the wood ray. The wood ray is the ribbonlike strand of tissue extending in a radial direction across the annual rings of the wood structure.
Fines account for about 10 to 20% of the material in a hardwood Kraft pulp. They have little value for papermaking purposes because they appear in the pulp as very short, thin-walled fragments. Fines reduce pulp strength to a significant degree, inhibit drainage, reduce one pass retention on paper machine wire, and also cause pitch deposits.
The paper industry has frequently sought better applications for fines. U.S. Pat. No. 4,547,263 teaches that parenchyma cells are useful in the manufacture of pressed board, charcoal briquettes, pressed granules for activated carbon, and as refuse derived fuel for boilers.